Form run-out and jam detector for printer

ABSTRACT

An error counter counts the lines moved by a continuous form tractor. The error counter is reset by pulses generated by a detector connected to detect feed holes in the form as they pass. If the form jams, a form run-out occurs, or forms shingling occurs with multiple forms, the feed hole pulses are interrupted and the error counter advances to a predetermined error count, producing an error output signal to stop the machine and/or activate an error indicator.

United States Patent 1191 Casale et a1.

[ Dec. 18, 1973 FORM RUN-OUT AND JAM DETECTOR FOR PRINTER [75] Inventors: William R. Casale, Endwell; Fred Saltz, Binghamton, both of N.Y.;

George R. Schreck, Montrose, Pa.; Emanuel V. Tomassini, Endwell, NY.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: Apr. 20, 1972 [21] Appl. No.: 246,052

[52] US. Cl 226/74, 226/100, 197/133 R,

235/92 PE, 340/259 [51] Int. Cl. G03b 1/30 [58] Field of Search 226/100, 24, 45,

226/74, 75, 9; 197/133 R; 235/15ll22, 235/151.1, 92 DP, 92 PE, 92 SB, 92 V; 340/259;

[56] References Cited UNITED STATES PATENTS 4/1972 Piccione 197/133 R 3,558,862 1 1971 McMillan 73/157 x 3,414,671 12/1968 Meisingset et a1. 340/259 X 3,370,286 2/1968 Buss 340/259 2,983,357 5/1961 Estrems et a1. 197/133 3,499,516 3/1970 Schaaf 197/133 Primary Examiner-Allen N.'KnOWl6S Attorney-Francis V. Giolma et a1.

[ 5 7 ABSTRACT An error counter counts the lines moved by a continuous form tractor. The error counter is reset by pulses generated by a detector connected to detect feed holes in the form as they pass. If the form jams, a form run-out occurs, or forms shingling occurs with multiple. forms, the feed hole pulses are interrupted and the error counter advances to a predetermined error count, producing an error output signal to stop the machine and/or activate an error indicator.

4 Claims, 4 Drawing Figures FORM RUN-OUT AND JAM DETECTOR'IFOR PRINTER FIELD OF THE INVENTION DESCRIPTION OF PRIOR ART Heretofore, detectors have been used with special marks on forms and shifting registers to control the feed of forms and detect the beginning and end of forms in a continuous web, as described in U. S. Pat.

No. 3,123,195, which issued on Mar. 3, 1964, to A. R. Hewitt et al., and the feed holes have likewise been used for controlling feed of forms, as described in U. 8.

Pat. No. 3,323,700, which issued on June 6, 1967, to H. Epstein et al.

SUMMARY OF THE INVENTION Generally stated, it is an object of this invention to provide a new and novel jam detection system for a continuous form in a high speed printer.

More specifically, it is an object of this invention to provide for sensing the feed holes in a continuous form or forms being fed in a printer and using this to control a counter connected to provide a line count obtained from movement of the forms feed mechanism.

Another object of the invention is to provide for using a detector to sense feed holes adjacent the edge of a continuous form as it is fed, using a line count from the form feed tractor mechanism for operating an error counter, resetting the error counter by output pulses from the detector and using a predeterminederror count in the counter as evidence of a failure of the form to feed as it should.

Yet another object of the invention is to provide a form jam detector which will also operate to detect run-out of the form. i

Still another object of the invention is to provide a form jam detector which can also detect undesirable shifting orv shingling of one or more of a plurality of forms in a multi-partform, but is unaffected by shingling of the carbons only.

Another object of the invention is to provide a failsafe form jam detection system.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more detailed description of preferred embodiments of the invention, as illustrated in the accompanying drawing.

DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a schematic partial end view of a forms feed tractor showing how the feed hole detector is mounted relative to the form;

FIG. 2 is a schematic partial front view of the form feed tractor of FIG. 11;

FIG. 3 is a schematic circuit diagram of a line counter and an error counter connected to operate in accordance with one embodiment of the invention; and

FIG. 4 is a partial end view of a form feed tractor showing a different arrangement for a feed hole detector which may be used in practicing the invention.

DESCRIPTION OF'PREFERRED EMBODIMENTS Referring to FIGS. l and 2, the reference numeral 10 denotes generally a portion of a forms feeding Tractor for feeding a Form or Forms 12, which is provided with a plurality of sprocket feed Holes I4 adjacent an edge thereof. The Tractor 10 may comprise an endless Toothed Belt 16 having a plurality of Teeth I8 about the inner periphery for engagement with a toothed drive wheel (not shown) on a Drive Shaft 20. The Belt 16 may be provided with a plurality of uniformlyspaced lateral Projections 22 along one edge having outwardly projecting Pins 24, which are spaced to be positioned in the Holes 14 of the Document T2 for feeding it. The Tractor It) has a hinged Cover or Door 25 which may be mounted by a pair of hinges only one of which, Hinge 26, is shown, in order to be swung outwardly to permit a form or forms to be placed on the Tractor 10 with the Pins 24 in the Feed Holes 14.

In order to detect whether the Form 12 is feeding properly a light source such as a light-emitting Diode 30 may be mounted in front of the Form 12 by means of a Bracket 32 on the hinged Cover 25, and a lightsensitive device such as a Photo-transistor 34 may be mounted on the opposite side of the Form I2 in alignment with the Holes 1141 so as to receive light from the Diode 30 through the Holes 14 and detect passage of the Holes as they pass between the light-emitting diode and the photo-transistor. An Emitter Wheel 36 is mounted on the Tractor Drive Shaft 20 to move with operation of the Tractor 10, having a plurality of Slots 38 about the periphery which are sensed by means of Transducer 40, which may be a magnetic transducer.

The emitter signal from the Transducer 4th is applied to an Amplifier 42, which as shown in FIG. 3, is connected to drive a Counter 4L4, which is arranged to count the lines that the Form I2 advances. Gates such as AND 46 and AND 4% may be connected to the Counter ME- for providing outputs each time the form advances one line. When using an ErnitterWheel 36 having'Slots 3% every 5, for example, the AND 46 may be'connected to the 4 count output of the Counter 44 and gated by means of a six lines per inch signal when the printer is operating a pitch of six lines per inch. The AND 38 may beconnected to the 3 count output of the Counter 4 and gated by means of an eight lines per inch signal when the printer is operating at a pitch of eight lines per inch. ANDs 46 and 48 are connected to an OR SID to provide an output to advance an Error Counter 54 one advance each time the Form 12 advances one line.

The output of the Photo-transistor 34 is connected by means of an Amplifier 56 and a Single Shot 5% to reset the Counter 5 each time a Hole 14 passes the Phototransistor 34 and Diode 30. ANDs 6t) and 62 are connected to selected outputs of the Counter 54, for example, the 9 count, the 7 count outputs, being gated by an eight line per inchsignal and a six line per inch signal, respectively. ANDs 60 and 62 are connected to an OR 64 to provide an error signal which may turn on an indicator or stop the print, or both. i

In operation, pulses from the Emitter Wheel 36 operate the Line Indicator M through Amplifier 42 and provide outputs at the ANDs $6 and 41a, depending on which line pitch mode the printer is operating in, that is, six lines per inch or eight lines per inch. This line count advances the Error Counter 541 through Amplitier 52 each time the form advances one line. At the same time pulses from the Photo-transistor 34 and light-emitting Diode 30 are applied to the Amplifier 56 and Single Shot 58 to reset the Error Counter 54 each time a Hole 14 passes the Photo-transistor 34 and permits light from the Diode to impinge on the Phototransistor. Therefore, if the form is feeding normally, since the holes are spaced at half-inch intervals, the Error Counter 54 will be reset each time it reaches a count of 3 or 4, depending on whether it is operating in the six lines per inch or the eight lines per inch mode. Should the forms fail to advance properly, the Emitter Wheel 36 will continue to produce pulses advancing the Line Indicator 44 and causing the Error Counter 54 to advance, but if the Holes 14 are not passing between the Light-emitting Diode 30 and the Photo-transistor 34, the Error Counter 54 will not be reset, hence, the count of the Counter 54 will exceed the 6 or 8 count value for two holes at six lines per inch and eight lines per inch, respectively, and an output will be produced by one of the ANDs 60 or 62, depending on which mode the printer is operating in. An error signal will be produced at the output of the OR 64 to either turn on an indicator and/or stop the printer under these conditions.

Referring to FIG. 4, the reference numeral 10 denotes generally a forms feeding tractor of the same type as shown in FIGS. 1 and 2, having a Toothed Belt 16 provided with projecting Pins 24 for feeding a Form 12. Instead of mounting a light source on one side of the Form 12 and a light-sensitive device on the other side of the form, a light-emitting Diode 66 may be mounted behind the Form 12 and a Photo-transistor 68 mounted on the same side of the Form 12 to detect light reflected from the surface of the Form 12, as it passes. A layer of Glass 70 may be positioned between the lightemitting diode and the document to protect the diode.

In normal operation light is reflected from the Form 12 to the Photo-transistor 68 and the passage of a Hole 14 will interrupt the reflected light giving an indication of a hole. The Tractor Shaft is provided with an Emitter 36 which may be connected to the Amplifier 42 for providing a line count for advancing the Error Counter 54. The Photo-transistor 68 may be connected to the Amplifier 56 for resetting the Error Counter 54 each time a hole passes the light-emitting Diode 66. This form of sensing is just-a effective as that described in connection with the arrangement of FIGS. 1 and 2 and has the advantage that while it is sensitive to shingling of plural forms which cause the Holes 14 to be closed off, it is unaffected by the shingling of the carbons alone, since when the carbons block the Holes 14, they still operate as non-reflecting surfaces.

From the above description and the accompanying drawing, it will be seen that we have provided a simple and effective forms feeding detector requiring only a single detector which is highly reliable, since the detector is a solid state device supported by electroniclogic. The speed of reaction is adjustable and may be made faster or slower as experience dictates. Adjustment is made by changing the error count, i.e., the ,count that is reached which causes an error to be signaled by the logic circuits. A wide range of forms thickness and weights can be handled without adjustment. Ifajam occurs in the tractor, the paper either stops moving or is skewed off the tractor pins. No holes pass the detector and the Error counter continues to count. When the error count is reached a jam is indicated and an output signal is produced which causes the printer to stop. Also, when the last form passes the detector, no more resets to the Error counter will be generated and the printing will stop when the error count is reached. Thus, the jam detector can serve also as an end of forms or run-out detector. The reflector design of FIG. 4 offers additional advantages over the SEE- TI-IROUGI-I arrangement of FIGS. 1 and 2 in that it is failsafe, so that if either of the components fail, an error will be detected. It is also a single piece design, thus facilitating packaging and it is not affected by carbon paper shingling in multipart forms.

While the invention has been particularly shown and described with reference to preferred embodiments thereof it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is: t

1. Error detection means for form feeding means having drive means with a plurality of projecting pins spaced to fit in a plurality of uniformly spaced feed holes in a form comprising,

an error counter producing an error output in response to a predetermined count,

means to detect said holes as saidform moves past connected to said error counter to reset said error counter,

a line indicator counter having a plurality of outputs operated by said drive means and having at least one of said outputs connected to said error counter to advance said error counter one count each time said form feed means advances said form one line, and

means including an emitter driven by said form feed means to produce output pulses for each predetermined increment of form feed means advance connected to operate said line indicator counter each time said form advances one line.

2. The invention as defined in claim 1 characterized by said means'for detecting holes comprising a light source-and a photo-transistor positioned on the same side of said form in alignment with said holes to operate in response to interruption of light reflected from said form due to passage of said holes.

3. The invention as defined in claim 1 characterizedby said line indicator counter having gate means selectively connecting different ones of said plurality of outputs to said error counter to advance said error counter one count for each line advance of the form for different values of line pitch.

4. The invention as defined in claim 3 characterized by said error counter having a plurality of outputs and gate means selectively responsive to different line pitch values connecting said outputs to provide an error signal when said error counter reaches a predetermined GI'I'OI' count. 

1. Error detection means for form feeding means having drive means with a plurality of projecting pins spaced to fit in a plurality of uniformly spaced feed holes in a form comprising, an error counter producing an error output in response to a predetermined count, means to detect said holes as said form moves past connected to said error counter to reset said error counter, a line indicator counter having a plurality of outputs operated by said drive means and having at least one of said outputs connected to said error counter to advance said error counter one count each time said form feed means advances said form one line, and means including an emitter driven by said form feed means to produce output pulses for each predetermined increment of form feed means advance connected to operate said line indicator counter each time said form advances one line.
 2. The invention as defined in claim 1 characterized by said means for detecting holes comprising a light source and a photo-transistor positioned on the same side of said form in alignment with said holes to operate in response to interruption of light reflected from said form due to passage of said holes.
 3. The invention as defined in claim 1 characterized by said line indicator counter having gate means selectively connecting different ones of said plurality of outputs to said error counter to advance said error counter one count for each line advance of the form for different values of line pitch.
 4. The invention as defined in claim 3 characterized by said error counter having a plurality of outputs and gate means selectively responsive to different line pitch values connecting said outputs to provide an error signal when said error counter reaches a predetermined error count. 